JPH04136452A - Supercharger for engine - Google Patents

Abstract

PURPOSE:To increase the number of revolution in prerevolution by retarding the ignition timing immediately before the prerevolution of a high load supercharger, in the constitution in which a low load supercharger and the high load supercharger are installed and the high load supercharger is put into prerevolution before drive. CONSTITUTION:During the engine operation, an ECU 46 judges if the engine operation state at present is in a region (P+S region) for driving both of a primary turbosupercharger 4 and a secondary turbosupercharger 6. If the judgement is 'YES', it is judged if the engine operation state is in both the supercharger driving state or not, and if the judgement is 'NO', a prerevolution time setting timer and a retard control setting timer for ignition timing are started. Then it is judged if the prerevolution time setting timer counts up or not, and if the judgement is 'NO', the ignition timing in an ignition timing retard control time is retarded, and the temperature of the exhaust gas is raised. Accordingly, the number of revolution in prerevolution of the secondary turbosupercharger 6 is increased speedily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mechanical supercharging device for an engine.

(Prior art) Recently, it has been possible to improve efficiency over the entire operating range of an engine by using two sets of mechanical superchargers with different capacities, one for low load and one for high load, depending on the operating state of the engine. A mechanical supercharging device that performs intake air supercharging is well known as a so-called sequential twin turbo charger (see, for example, Japanese Utility Model Application Publication No. 178329/1983).

In such a sequential twin turbo charger type supercharging system, the state is switched from a state in which only the low-load supercharger is being driven to a twin state in which the high-load supercharger is driven at the same time. There is a problem with a transient torque drop when the Therefore, for example, a pre-rotation system is generally employed in which the low-load supercharger is pre-rotated in advance of the switching.

(Problem to be solved by the invention) However, when the above-mentioned pre-rotation system is adopted,
When the acceleration itself is very large, such as during sudden acceleration from the low-load supercharger drive region, the pre-rotation itself becomes insufficient (the rise in rotational speed is insufficient) due to so-called turbo lag, and the desired speed is not increased. A problem arises that prevents the goal from being achieved.

(Means for Solving the Problems) Each of the inventions recited in claims 1 and 2 of the present application has been made for the purpose of solving the above-mentioned problems, and is configured as follows.

(1) Structure of the engine supercharging device according to the invention as claimed in claim 1 The engine supercharging device according to the invention as claimed in claim 1 comprises a low-load supercharger and a high-load supercharger, each of which is equipped with an exhaust turbine. There are two sets of superchargers with the engine, and depending on the operating state of the engine, the driving state of only the low-load supercharger to the driving state of both the low-load supercharger and the high-load supercharger. and a switching means for arbitrarily switching the supercharger driving state, and the high-load supercharger is switched and driven by the switching means by supplying a part of the exhaust gas to the exhaust turbine of the high-load supercharger. The engine is pre-rotated in advance, and is characterized by being provided with ignition timing retard means for retarding the engine ignition timing by a predetermined amount immediately before the pre-rotation of the high-load supercharger. .

(2) Structure of the engine supercharging device according to the invention recited in claim 2 The engine supercharging device according to the invention recited in claim 2 is configured as described in claim 1.
The engine supercharging device described above is configured to cancel the retardation of the ignition timing after a predetermined period of time.

(Function) (1) Effect of the engine supercharging device of the invention claimed in claim 1 In the structure of the engine supercharging device of the invention claimed in claim 1,
The driving state of the supercharger is switched from low load to both low load and high load depending on the operating state of the engine. Immediately before switching the supercharger, the ignition timing is retarded for a predetermined period of time to raise the temperature of the exhaust gas, thereby increasing the exhaust gas volume and increasing the rotational speed during pre-rotation of the high-load supercharger. It works to make it as high as possible.

(2) Effect of the engine supercharging device according to the invention claimed in claim 2 In the structure of the engine supercharging device according to the invention claimed in claim 2, the retard of the ignition timing in the invention described in claim 1 is adjusted to a predetermined value. After a period of time has elapsed, for example, when the rotation of the high-load supercharger has increased sufficiently, it is released.

(Effects of the Invention) Therefore, according to the engine supercharging device of the present invention, there is no torque drop when switching the supercharger even during sudden acceleration, and the supercharger switching is performed with a smooth feeling of continuity. Become.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings of FIGS. 1 to 5.

FIG. 1 shows a turbocharged rotary piston engine of the 20-ta type, for example, which is equipped with an intake system for a supercharged engine according to an embodiment of the present invention. The supercharging system for this engine is a so-called sequential turbo type that includes a primary turbo supercharger and a secondary turbo supercharger. In FIG. 1, reference numeral 1 denotes the same engine, and the exhaust passages 2 and 3 of each cylinder are provided in parallel and independently of each other. A turbine 5 of a primary turbocharger 4 is disposed in one of these two exhaust passages 2 and 3, and a turbine 7 of a secondary turbocharger 6 is disposed in the other. That is, in this engine 1, the exhaust passages 2.3 of each cylinder are independently connected to both the primary and secondary exhaust turbo superchargers 4.
．． 6f) By guiding the exhaust gas to 9-bin 5.7, mutual interference between exhaust gases in the supercharging region (P+S region in Figure 4) where supercharging is performed by both exhaust turbo superchargers 4 and 6 is eliminated, and the exhaust movement is improved. The pressure is effectively applied to both turbines 5 and 7 to improve supercharging efficiency. The two exhaust passages 2 and 3 join together downstream of both the turbines 5 and 7 to form one exhaust passage 24.

Further, the intake passage 9 is divided into two downstream of an air cleaner (not shown), and the blower 11 of the primary turbocharger 4 is located in the middle of the first branch passage 10, and the blower 11 of the primary turbo supercharger 4 is located in the middle of the second branch passage 12. A blower 13 of a secondary turbo supercharger 6 is provided respectively. These branch passages10.12
are formed so as to face each other at the branching portion and to extend substantially straight on both sides. Furthermore, the two branch passages 10 and 12 do not merge downstream of the blowers 11 and 13, but extend independently and in parallel to each other and are connected to the two intake ports 17 and 18 of the engine 1.

Intercoolers 14a and 14b are disposed in the middle of the two intake passages 9a and 9b in this part, respectively, and surge tanks 15a and 15b are further disposed downstream of the intercoolers 14a and 14b, and intercoolers 14a and 14b and surge tank 15a, 15b and a throttle valve 16a.

16b are arranged respectively. The throttle valve 16a1
6b are mutually connected to the electric actuator 60 via link rods. In addition, the intake passages 9a, 9
b has two independent intake ports 17.18 at the downstream end, and each intake port 17.18 is independently provided with a fuel injection valve 19, 20, respectively.

On the other hand, on the upstream side of the intake passage 9, an air flow meter 21 is provided upstream of the branch of the first and second branch passages 10.12 to detect the amount of intake air.

The two exhaust passages 2 and 3 are communicated with each other by a relatively small diameter communication passage 22 upstream of both the primary and secondary exhaust turbochargers 4 and 6. In the exhaust passage 3 in which the secondary turbine 7 is disposed, an exhaust cut valve 23 is provided immediately downstream of the opening position of the communication passage 22. The exhaust cut valve 23 is of a so-called normally closed type. That is, a diaphragm type actuator 31 is connected to the exhaust cut valve 23 via a link. A spring 31a is provided within the actuator 31 to always bias the exhaust cut valve 23 in the closing direction. Therefore, when the engine is not operating, the actuator 3
1 does not operate, the exhaust cut valve 23 closes under the biasing force of the spring 31a. On the other hand, when the actuator 31 is turned on during engine operation, the exhaust cut valve 23 receives the operating force of the actuator 31, and the exhaust cut valve 23 closes due to the biasing force of the spring 31a. The exhaust cut valve 23 is opened by rotating clockwise in FIG. 1 against the exhaust dynamic pressure on the upstream side of the cut valve 23.

Further, a wastegate passage 25 is formed which communicates with the confluence exhaust passage 24 downstream of the turbines 5 and 7, and a wastegate valve 27 to which a diaphragm type actuator 26 is linked is connected to the wastegate passage 25.
is installed.

An exhaust leakage passage 28 is provided that communicates the wastegate valve upstream portion of the wastegate passage 25 with the exhaust cut valve downstream portion of the exhaust passage 3 connected to the secondary turbine 7. The exhaust leakage passage 28 is provided with an exhaust leakage valve 30 linked to a diaphragm type actuator 29 .

In addition, a blower 13 is installed in the branch passage 12 on the secondary side.
A relief passage 34a is formed to bypass the
A diaphragm type secondary intake relief valve 35a is disposed in the relief passage 34a.

The pressure chamber of the actuator 29 that operates the exhaust leak valve 30 is connected via a conduit 36 to the blower 11 of the branch passage 10 in which the blower 11 of the primary turbocharger 4 is disposed.
It is connected downstream. When the pressure on the downstream side of the blower 11 exceeds a predetermined value, the actuator 29 operates to open the exhaust leakage valve 30, thereby allowing a small amount of exhaust gas to flow into the exhaust leakage passage 28 when the exhaust cut valve is closed. and is supplied to the secondary turbine 7.

Therefore, the secondary turbo supercharger 6 starts rotating in advance (pre-rotation) before the exhaust cut valve 23 opens.

Further, the actuator 31 that operates the exhaust cut valve 23 is a differential pressure type actuator that is operated by the difference in pressure acting on two pressure chambers, and the pressure chamber in which the spring 31a is disposed is connected to the conduit 39a. It is connected to the output port of the electromagnetic solenoid type three-way valve 4.0a. Furthermore, the pressure chamber of the actuator 41a that operates the secondary side intake relief valve 35a is connected to the conduit 42g.
is connected to the output port of another electromagnetic solenoid type three-way valve 43a. Secondary side intake relief valve 35
As will be described later, the exhaust cut valve 23 is opened (the relief passage 34a is kept open until a predetermined time).As a result, the secondary turbo supercharger 6 is activated by the exhaust gas flowing through the exhaust leakage passage 28. When rotating, the pressure upstream of the intake passage 9b increases to prevent it from entering the surging region.

The actuator 26 for operating the wastegate valve 27 is connected by a conduit 44 to the output port of another three-way valve 45 of the electromagnetic solenoid type.

Then, the three electromagnetic solenoid type three-way valves 40a, 4
3a, 45 and the two fuel injection valves 19, 2o are controlled by an engine control unit 46 configured using a microcomputer. Then, the engine control unit.

46 includes an output signal of an engine rotation speed sensor 61 (engine rotation speed detection means), an output signal of a secondary turbocharger opening sensor 62, and an accelerator operation amount sensor 64 that detects the operation amount and operation acceleration of the accelerator pedal. (load request detection means) output signal, air flow meter 21 output signal, Igni.

John switch signal (detection of energized or not)
In addition, the manifold pressure P1 downstream of the primary side blower 11, the opening degree of the waste gate passage 25, etc. are input.

Further, one input port of the three-way valve 40a for controlling the exhaust cut valve 23 is open to the atmosphere, and the other input port is connected to the blower downstream side intake passage 9a of the primary turbocharger 4 via a conduit 52. It is connected to a negative pressure tank 48 that communicates with. Therefore, the actuator 31 that operates the exhaust cut valve 23 is operated by the differential pressure between the intake manifold pressure downstream of the primary side blower guided through the conduit 47 and the intake negative pressure guided through the conduit 52 and the conduit 47. Operate.

On the other hand, one input port of the three-way valve 43a for controlling the secondary intake leaf valve 35a is connected to the negative pressure tank 48, and the other input port is open to the atmosphere. Further, one input port of the three-way valve 45 for controlling the wastegate valve 27 is open to the atmosphere, and the other input port is connected to the above-mentioned conduit 36 communicating with the downstream side of the primary side blower 11 via a conduit 54b. .

On the other hand, in the exhaust force y) valve 23, when the three-way valve 40a for controlling the exhaust cut valve 23 is OFF, the conduit 39a is opened to the atmosphere, and the exhaust cut valve 23 is closed by the biasing force of the spring 31a of the actuator 31. . On the other hand, when both the three-way valves 40a are turned on, the actuator 31
The primary side manifold pressure P is guided to the pressure chamber of the other spring 31. through the conduit 39a. a
Negative pressure is generated in the pressure chamber in which the pressure chamber is located, and the actuator 31 receives this relative pressure difference to generate an exhaust force.

Overcoming the high back pressure (exhaust dynamic pressure) acting on the exhaust upstream side of the cut valve 23, the exhaust cut valve 23 quickly opens, and supercharging by the secondary turbo supercharger 6 is performed.

The secondary side intake relief valve 35a connects the conduit 42a connected to the pressure chamber of the actuator 41a for operating the secondary side intake leaf valve 35a to the negative pressure tank 48 when the three-way valve 43a for controlling the secondary side intake leaf valve 35a is OFF.
When the three-way valve 43 is turned on and the conduit 42a connected to the pressure chamber of the actuator 41 is opened to the atmosphere, it is closed.

In addition, an actuator 26 for operating the waste gate valve 27
communicates downstream of the primary blower 11 via conduits 54b and 36 when the three-way valve 45 for controlling the wastegate valve 27 is on, and is opened to the atmosphere when the three-way valve 45 is off.

Next, the control operation of the ignition timing by the engine control unit 46 according to the driving state of each turbocharger 4, 6 will be explained in detail with reference to the flowchart of FIG. 2.

That is, first in step Sl, the engine rotational speed Ne,
Read each throttle opening TVO.

Next, in step S, a supercharging area map that is set widely on the low rotation side in consideration of the pre-rotation area shown in FIG. The current engine operating state using the opening TVO as a parameter is the primary turbo supercharger 4 described above.
and the area where both the secondary turbocharger 6 and the secondary turbocharger 6 should be driven (
It is determined whether or not it is in the P+S region (including the pre-rotation shown in FIG. 4).

As a result, if the determination is YES in the P+S region, the process further advances to step S4 and the value of the supercharger drive flag F is set to F−.
1 (both turbochargers are driven), and determine whether F=
1 (YES), the step s S+ s is jugged and the process proceeds to step S7, while the supercharger drive flag F is
When only the primary supercharger 4 is driven with the value F=O (No), the next step S is performed.

After setting the same flag F to F=1 (P+S) for the first time,
Further, the process advances to step S8 and the pre-rotation time setting timer T8 is set.
, ignition timing retard control time setting timer T, and step S.

Proceed to.

In step S, it is determined whether or not the pre-rotation time setting timer T has counted up, and if the determination is YES that the timer T has counted up, step S8
Proceeding to step 1, the above-mentioned exhaust force is applied, and the cut valve 23 is opened to increase the amount of exhaust gas supplied to the secondary turbo supercharger 6, as well as raise the exhaust gas temperature and increase the combustion gas volume. As a result, the secondary turbo supercharger 6 is driven,
The rotation speed increases rapidly. On the other hand, the same timer T1
If the determination is No that the count has not yet counted up, the process proceeds to step S, where the ignition timing retard control time T is retarded by 1 g of the ignition timing, and then the process returns. Furthermore, in synchronization with the retardation of the ignition timing, the air-fuel ratio is corrected in the rich direction as necessary (see FIGS. 3d and 3e). As a result, as shown in FIG. 3(c), the temperature of the exhaust gas rises and its volume also increases. Therefore, the rotational speed of the secondary turbocharger 6 during pre-rotation increases rapidly. As a result, Figure 3(a)
As shown in , torque down no longer occurs during acceleration.

When the above-mentioned exhaust cut valve 23 is opened in step S, it is further determined in step S10 whether or not the ignition timing retard control time setting timer T has counted up, and the timer T! When is counting up,
If (YES), proceed to step S and gradually decrease the above-mentioned ignition timing retard amount (.

On the other hand, unlike each of the above cases, if it is determined in step S3 that the region is not in the P+S region of FIG. Determine whether the value is F=0 (primary-single).

As a result, if the determination is No, the next step S13
Proceed to step S14 to newly set F=O.
Then, the exhaust gas is canted by controlling the above-mentioned exhaust force/7 valve to close.

Therefore, according to the configuration of the above embodiment, for example, (
As shown in a), in the first speed gear selection state, full throttle acceleration is performed and the state shifts to the drive region (p 10s ) of both the primary and secondary superchargers shown in FIG. In this case, the ignition timing is retarded by a predetermined crank angle for a predetermined period of time prior to the transition, and the air-fuel ratio A/F is further corrected to the rich side by a predetermined value as necessary. As a result, the amount of afterburning increases, the temperature of the exhaust gas rises as shown in FIG. 5(c), and the volume of the exhaust gas increases. As a result, the rotational speed of the secondary turbocharger 6 during pre-rotation can be effectively increased as shown in FIG. 5(b).

As a result, it is possible to maintain engine output as high as possible, and unlike before, it is possible to suppress the effect of turbo lag as much as possible, and the acceleration characteristics at full throttle acceleration as described above can be improved. It becomes possible to achieve the desired characteristics without torque down as shown by the solid line in FIG. 5(a).

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an engine supercharging device according to an embodiment of the present invention, FIG. 2 is a flow chart showing ignition timing control operation in the same embodiment device, and FIG. The time chart of the control operation shown in Fig. 4 is the same as the above-mentioned second
The supercharging area map used in the control operation shown in Figure 5 is as follows:
2 is a time chart illustrating the characteristics of the operation of the present embodiment when both the low-load supercharger and the high-load supercharger are driven in relation to the problems of the conventional device. 1゛・・・Rotary piston engine 2.3 ・
...Exhaust passage 4 ...Primary turbo supercharger 5 ...
Turbine 6... φ ・ ・ 23 ・ ・ ・ 46 ・ ・ ・

Claims (1)

[Claims] 1. Two sets of superchargers, a low-load supercharger and a high-load supercharger, each equipped with an exhaust turbine, and a low-load supercharger depending on the operating state of the engine. and a switching means for arbitrarily switching the supercharger drive state from a drive state of only a supercharger to a drive state of both a low-load supercharger and a high-load supercharger, In an engine configured to pre-rotate the high-load supercharger by supplying part of the exhaust gas to the exhaust turbine before switching drive by the switching means, the high-load supercharger is pre-rotated. A supercharging device for an engine, comprising an ignition timing retard means for retarding the engine ignition timing by a predetermined amount immediately before engine rotation. 2. The engine supercharging system according to claim 1, wherein the retardation of the ignition timing by the ignition timing retard means is canceled after a predetermined period of time.